Explainer
How does a water filtration system work?
Sediment, activated carbon, fine media, reverse osmosis and UV — what each filtration stage actually removes, and how to choose between point-of-use and whole-house systems.
Every filtration system does the same basic job: water passes through one or more treatment stages, and each stage removes something different. Understanding the stages helps you choose the right system — and avoid paying for one you do not need.
Stage 1: Sediment filtration
A sediment filter is a physical sieve, usually a spun polypropylene cartridge rated in microns. It traps sand, silt, rust and other particles. This protects everything downstream — including the more expensive cartridges that follow it.
Stage 2: Activated carbon
Activated carbon works by adsorption: chlorine, organic compounds and the chemicals that cause unpleasant taste and odour bind to the carbon's enormous surface area. This is the stage that makes municipal water taste clean.
Stage 3: Fine and specialty media
Advanced systems add a third stage. Disruptor media, for example, uses electropositive charge to capture bacteria, viruses and extremely fine particles down to 0.2 microns — far smaller than a standard sediment cartridge can catch. Reverse osmosis goes further still, forcing water through a membrane that removes dissolved salts and contaminants.
Disinfection: UV light
Filtration removes things from water; disinfection neutralises living organisms in it. An ultraviolet (UV) lamp damages the DNA of bacteria and viruses so they cannot reproduce. UV is a common final safeguard on borehole, well and tank supplies, where microbial quality can change with the season.
Point of use versus point of entry
A point-of-use system treats one tap — typically an under-counter unit with its own drinking-water tap in the kitchen. A point-of-entry (whole-house) system is installed on the main supply line, so every tap, shower, geyser and appliance receives treated water. Many homes combine both: whole-house filtration for general protection, plus a finer drinking-water system in the kitchen.
Start with a test
The right system depends on what is actually in your water. A SANS 241 water analysis measures the key safety and aesthetic parameters, and lets us specify treatment around facts rather than guesswork. Book a water test and we will recommend the stages your water genuinely needs.